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module Treetop
module Compiler
class Choice < ParsingExpression
def compile(address, builder, parent_expression = nil)
super
begin_comment(self)
use_vars :result, :start_index
compile_alternatives(alternatives, parent_expression)
end_comment(self)
end
def compile_alternatives(alternatives, parent_expression)
obtain_new_subexpression_address
alternatives.first.compile(subexpression_address, builder)
builder.if__ subexpression_success? do
# Undo lazy instantiation:
builder << "#{subexpression_result_var} = SyntaxNode.new(input, (index-1)...index) if #{subexpression_result_var} == true"
assign_result subexpression_result_var
extend_result_with_declared_module
extend_result_with_inline_module parent_expression
end
builder.else_ do
if alternatives.size == 1
reset_index
assign_failure start_index_var
else
compile_alternatives(alternatives[1..-1], parent_expression)
end
end
end
def expected
'"(any alternative)"'
end
end
end
end
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